Will climate change make storms more severe?

And how can Houston prepare for the storm that comes after Harvey?

For some area apartment dwellers facing a deadline to vacate their residences, the only way to return to their flooded complex is with a boat.﻿

For some area apartment dwellers facing a deadline to vacate their...

German soldiers had surged across vulnerable countryside toward Paris within weeks of their World War I invasion. Fearful that a second war was looming, French generals made sure to heed the lessons of the war before. They built hundreds of miles of fortresses, air-conditioned garrisons and even underground railways along their eastern border, fortified to withstand barrages from tanks and planes.

Protected by this Maginot Line, France was fully prepared to fight the last war. But the Germans fought a new one. Their blitzkrieg outflanked the Line, capturing Paris in a month.

In the decade since Hurricane Ike, have we too been fighting the last storm? And as we pick ourselves up from Hurricane Harvey, how can we better prepare for the next weather and climate disaster?

Hurricanes Ike and Harvey each took a brutal toll on our region. But they did so in different ways.

HURRICANE IKE smashed directly over Galveston and Houston on my birthday in 2008. But within two days, weather patterns had steered Ike across the Canadian border.

Ike wreaked its damage with 110-mph winds and substantial storm surge, destroying roofs, knocking trees into buildings and flooding coastal communities. Its damage to property ranked second only to Hurricane Katrina at the time.

Terrible as Ike was, experts quickly recognized that it could have been far worse. Ike weakened just before making landfall, sparing us from its most ferocious winds. And while a direct hit on Houston sounds ominous, it isn't a worst-case scenario. Storm-savvy Texans know the strongest winds, surge and rain from a hurricane occur not along the center, but on its right, "dirty" side.

Had Ike come ashore a bit southwest of town or at its peak intensity, we would have been pummeled by even stronger winds. Such a storm could have pushed more than a 20-foot storm surge into the Ship Channel, threatening catastrophic damage to refineries and chemical plants in its path.

Meanwhile, colleagues at Rice University proposed a Centennial Gate to prevent surge into the Ship Channel.

Like a Maginot Line, neither of those defenses would have protected us from Hurricane Harvey. Harvey came ashore even stronger than Ike, but 200 miles to our southwest. That left us safe from devastating storm surge and wind.

But in doing so, Harvey snuck behind what would have been the Ike-style defenses. It did so not with Ike's rapid blitz, but by plodding along while dropping deluges of rain.

Photo: Elizabeth Conley, Harvey2017

Harvey's rains classify it as what was thought to be a 1,000-year storm. In this photo: An apartment resident watches water accumulate in his parking lot on Saturday, Aug. 26, 2017.

Harvey's rains classify it as what was thought to be a 1,000-year storm. That comes on the heels of the Memorial Day Floods of 2015 and Tax Day Floods of 2016, each classified as 500-year events for Houston.

Maybe it's just that lightning has struck thrice. But few would mistake this as an opportunity to grow complacent, having endured in three years our share of megastorms for the next two millenia.

More likely, our warming climate has washed away our previous notions of the frequency of extreme events. Warmer waters mean more evaporation. And with warmer air, that moisture falls in more extreme events, as anyone who has experienced Texas thunderstorms and New England drizzle will know. Warm waters also provide the fuel that intensifies hurricanes and drives their gusting winds.

All these factors intensify the ferocity of Ike-style winds and surge, as well as the depths of Allison- and Harvey-style deluges. Far less certain is whether a climate-driven shift in the jet stream will impair the windflow needed to keep such storms from stalling.

SO HOW can we prepare for the next disasters? Unlike the French, we never actually built a mile of our proposed defenses against the last disaster.

Just because those defenses would have been worthless against Harvey doesn't mean they won't be crucial for our next Ike-style storm. But we also must prepare for catastrophic inland rains and flooding that no coastal defense can thwart.

Perhaps Houston will never again endure rains that were unprecedented in the history of the continental United States. But climate change will continue stacking the odds toward more extreme events. The world has warmed just 1 degree Celsius (2 degrees Fahrenheit) so far. Even fully achieving the goals of the Paris Agreement would double that; failing to act means risking an additional doubling, and the even more extreme weather events that would come with it.

Thus, we face a future when both deluges of rain and blitzes of wind and surge will become ever greater risks.

Evolving scientific understanding suggests that hurricanes might not become more frequent, but those that do form might become more severe and intensify with such astounding rapidity as Harvey did and Hurricane Patricia before it.

Photo: Karen Warren, Staff Photographer

Houston has endured in three years our share of megastorms for the next two millenia.

Houston has endured in three years our share of megastorms for the...

Even without Houston's urban planning woes, no city can fully protect itself from 140-mph winds, 25-foot surge, or 40 inches of rain that arrive with only brief warning.

As an atmospheric scientist, I don't have the answers for how to design the infrastructure, drainage and response systems needed to defend against the next storm. But I can say that past won't necessarily be prologue, and we'll need to be careful not to overlearn the lessons of history as we enter a future climate that tosses our old benchmarks away with the floods.

Daniel Cohan is an associate professor of environmental engineering and faculty scholar at Rice University's Baker Institute for Public Policy.